For the purpose of increasing the life of tools such as cutting tools and dies, the wear resistance of the tools has been conventionally improved in such a manner that surfaces of the tools are coated with a hard coating of, e.g., TiN, TiCN, or TiAlN.
In recent years, e.g., films with laminated structures described in Patent Documents 1 and 2 have been proposed as coatings formed on cutting tool surfaces. Specifically, Patent Documents 1 and 2 each disclose a laminated coating configured such that two or more coatings A made of a solid solution of Mo and N, Mo2N, MoN, or a mixture thereof and two or more coatings B made of Ti1-x-yAlxSiyN are alternately laminated on each other. In such a laminated coating, the layer thickness of each of the coatings A, B, the thickness ratio between the coatings A, B, and the gradient structure of layer thickness ratio in the cross section of the coating along a lamination direction are defined. Moreover, in this laminated coating, the coatings A exhibit lubricity and welding resistance, thereby effectively improving the quality of processing of a cutting target material and effectively reducing the temperature of a blade edge in high-speed dry processing. The coatings B exhibit excellent balance between wear resistance and toughness. However, since more superior wear resistance is required for, e.g., cutting tools, more study should be made.